beard



ASA n. BEARD, or rumsnono, NEW HAMPSHIRE.

Letters Patefit No. 74,483, dated February, 18, 1868.

, mesovsrmnrin GEARING.

TO ALL WHOM IT MAY CONCERN: A

Be it known that I, ASA BLI. BEARD, of Hillsboro, in the county of Hillsboro, and State of New Hampshire, have invented an Improvoment in Gearing; and I do hereby declare that the following, taken in connection with the drawings which accompany andform partof'this specification, is descri tion of my invention suificient to enable those skilled in theart 'to practise it.

This invention is designed'for the prevention of play or nnnecessary movement between the teeth of gears L which are meshed into each other, or,i' n' other words, according to technical usage, is designed to prevent backlash between two meshed gears.

Gears are rarely fitted so that one of a meshed pair cannot he moved without imparting movement tothe other; and even it so fitted, the abrasion of the teeth consequentupon wear soon all'ows play or back-lash. between the teeth.

Back-lash ordinarily does not interfere with the movements designed to be'produced by a train of-gearing,

because each pair of gears most commonly operates but one way, with but one fa'ce of each tooth of one subject to wear by onefa-ce of each tooth of the other gear; but where a reverse strain is brought upon one gear of a pair, then said gear is at liberty to move backward the amount permitted by the spaces left bctween the meshed teeth of the pair.

l It is where such reversed strains a'rliable to be brought upon meshed gears that my invention becomes of value; and I have illustrated myinventionhyits application to'the head-block or gauge-rest of a saw-milh;

where it'is dsirahlcto have the movement or set of the head-block or gauge free from yield which would be.

consequent upon back-lash in the gearingby which such head-block or gange isoperated. My invention consists in making one of a pairof meshing-gears in two parts, the divisionbetween the parts "being about midway of the length of the teeth, and in a plane at right angles to the axis of rotation, when one of said parts iskeyked to it s' shaft, and the other part is-loose upon said shaft, and is connected therewith only by means of a spring arranged to act by torsion, to cause a movement of the parts of the divided gear with respect to each other, so as to cause parts of the opp'ositefaces of'each divided tooth to bear against the opposite faces ofany two'a djacent teeth of the whole gear between which the divided tootlrmay happen to he, and thus prevent movement of the whole or wide gear exept such as operates to turn the shaft of the double or divided gear. Figaro Ishows a planhf' a saw-mill gauge-bar or head-block embodying my improvement in gearing.

Figure 2 is a partial horizontal section of the same; and r Figure 3 is a partial end view thereof on an enlargcdscale. r

In the drawings, the whole or wide gear a is shown. as fixed on the shaft 6 on which are two pinions, 0, designed to mesh into two racks on a saw-bench fiiame, so that by rotation of said pinions c, the gauge-bar may be .mo'ved toward and from the saw, the shaft 1) being mounted in bearings 01 fixedto the barf. To rotate the shaft 1), so as to cause forward movement of barf toward the saw, the lever e is pivotedion shaft b, and

hears apawl, g, which operates on the teeth of a, as onratchet-tceth, to turn said gear, consequent upon vibra; tions of lever e. To retain the gauge-bar in place against the pressure and action-of the saw, by keeping the gear a from rotativc movement, except I such as is imparted to it by lever e, there is provided a shziftph, mounted in bearings connected to the'gauge-barf. On said shaft is key ed fast a ratchet, i, and one half,j,of a divided i;

gear, the other half, 7:, being loose on the ,shaft it, though connected therewith by means of a helical spring, l, I

one end of said spring being fixed in the half gear 7a,.and the other end being fixed in the collar 111. made fast to the shaft h. This spring is so applied that it has a torsional effect on half gear, is, of sufficient power to turn the shaft h, the resnlt of thisbeing to keep one faceof a tooth of is against one face of a 'toothof a, at the same time that the opposite face of the fellow-tooth of j is kept in contact with the oppositeface of the-next tooth of a, between which and that tooth or a,just before referred to, the teeth ofjand lr,just mentionedpare meshed,

It will be seen, therefore, that there can be no movement of a which is not imparted to thesha-ft it, by reason of there being no play or hackvlash between the teeth of a and the teeth off and la. v

To keep the ratchet i from turning, there is applied to it the pawl n, which, whenthe gauge-harfis to be.

returned or brought back fromthe saw, is thrown out of gear with the ratchet-teeth-of i. A I claim, for the purpose specifie hin the construction and arrangement of apair'of meshinggears, dividing one gear in a plane square to Rs axis, shaft by'a spring, which operatesto tnr'n said part or its shaft with reference to each other.

In testimony whereof, I have hereto set my signature, this twenty-third day of October, A. D. 1867.

AVM. BEARD.

Witnesses:

' Fmncrs Gonna,

M. ,W. FnorHmeHAM.

andfixing one port on its shaft, while the other part is attached to said 7 

